简介：Becauseoftheexcellentmechanicalpropertiesof34C「NiMo6steel,itiswidelyusedinhigh-valuecomponents.Manyconventionalapproachestostrengthening-steelstypicallyinvolvethelossofusefulductility.Inthisstudy,34CrNiMo6Steelhavinghighstrengthandductilityisproducedbylasersolidforming(LSF)w让haquenching-tempering(QT)treatment.TemperingofbainiteismainlybysolidphasetransformationinthepreviousLSFlayersduringtheLSFprocess.ThestablemicrostructureofLSFconsistsofferriteandfinecarbides.Themicrostructuretransferstotemperedsorbiteafterheat-treatment.ThetensilepropertiesoftheLSFsteelmeetthoseofthewroughtstandard.TheUTSandelongationofLSFsampleat858MPa,19.2%,respectively,aregreaterthanthoseofthewrought.TheQTtreatmentenhancedtheultimatetensilestrengthandyieldstrengthoftheLSFsample.Theultimatetensilestrength,yieldstrength,reductioninarea,andelongationoftheLSF+QTsampleat980MPa,916MPa,58.9%,and13.9%,respectively,aregreaterthanthoseofthewroughtstandard.TheyieldstrengthoftheLSF+QTsampleisapproximately1.27timesthatofthewrought.TheLSFsamplesfailedinaductilefracturemode,whiletheLSF+QTsamplesshowedmixed-modefailure.ThedefectshaveonlyasmalleffectonthetensilepropertiesowingtotheexcellentductilityoftheLSFsample.

简介：Achievingnotonlyhighmechanicalstrengthsbutalsohighductilityisrecentlyestablishedusinganadditivemanufacturingtechniquecalledselectivelasermelting.Inthepresentstudy,stainlesssteel304Lfullydensesamplesweresuccessfullyprintedusingthe3Dsystems-ProX300printingmachine.TheductilityandtensileyieldstrengthwerealmosttwoandthreetimeshighercomparedtothoseofASTMcast'salloy.Honeycomblikenano-cellularstructurew让hdifferentorientationwasobservedinthefinegrains(-4μm)duetofastcoolingrate.Inadd让ion,theformationofmartensitephaseinrandomgrainsisalsoacontributortothestrengths.Furthermore,negativeresidualstressesinthebuildandhorizonraldirectionsweredetectedandassistedfurtherincreaseinthetensilestrength.Fractographyrevealedtheductilefeatureofplasticdeformationandthecrackopeningsatunmeltedparticlesorpores.